SPN-812 Reduces ADHD Symptoms in Phase 3 Study

Stefan Schwabe, MD, PhD

A phase 3 study of investigational drug SPN-812 for adolescents with attention-deficit/hyperactivity disorder (ADHD) has produced positive topline results. Patients receiving SPN-812 400 mg experienced a significant decrease in ADHD-RS-5 from baseline compared to those receiving placebo.

The study, P304, is the fourth phase 3 study of SPN-812 in a series of trials that evaluated 100 mg, 200 mg, 400 mg, and 600 mg doses versus placebo in pediatric patients.

“We are pleased with the final data confirming the positive results we announced in the previous phase 3 studies on SPN-812 last year in December,” stated Jack Khattar, President and Chief Executive Officer of Supernus Pharmaceuticals, in a statement. “We now have robust data on 100 mg, 200 mg, and 400 mg doses from all 4 phase 3 clinical trials with SPN-812 in patients with ADHD. The data are consistent in showing a clinically meaningful reduction in the symptoms of ADHD, with a favorable safety and tolerability profile.”

The double-blind study included 297 patients 12 to 17 years of age who were diagnosed with ADHD. Participants were randomized to SPN-812 400 mg, SPN-812 600 mg, or placebo. Treatments were given orally and daily over 7 weeks, with 1 week of titration for the SPN-812 400 mg group and 2 weeks of titration for the SPN-812 600 mg group.

After 7 weeks, the SPN-812 400 mg treatment reached statistical significance compared to placebo in the primary endpoint, change from baseline in ADHD-RS-5 total score. Participants receiving SPN-812 400 mg had a -18.3 LS Mean change from baseline (P = .0082) vs. LS Mean change of -13.2 from baseline for those receiving placebo.

Significant results were seen starting at week 2 for the SPN-812 400 mg dose compared to placebo (P = .0063) and continued through week 7 (P = .0082). Additionally, SPN-812 400 mg was effective compared to placebo on the hyperactivity/impulsivity (P = .0484) and inattention (P = .0042) subscales of the ADHD-RS-5 scale.

The trial demonstrated tolerability and safety profiles similar to the previous trials of SPN-812. Adverse events led to discontinuation rates of 4.0% to 5.1%. Treatment related adverse events that were observed at ≥5% incidence for SPN-812 were somnolence, fatigue, decreased appetite, headache, and nausea.

“In addition to the consistent and clinically meaningful efficacy data, we continue to be encouraged by the safety and tolerability of SPN-812 especially that the 600 mg dose showed a similar profile to the 400 mg dose,” stated Stefan Schwabe, MD, PhD, Executive Vice President R&D and Chief Medical Officer of Supernus Pharmaceuticals.

Schwabe noted that the safety profile for this range of doses would give providers flexibility in determining doses for their patients.

Khattar added that the company is working on a New Drug Application to submit to the US Food and Drug Administration (FDA) in the second half of 2019 that would include the 100 mg, 200 mg, and 400 mg doses of SPN-812, but not the 600 mg dose.